This invention relates to a wrench which can provide easy and rapid fastening or loosening of bolts, and more particularly to a mechanism thereof.
In fastening or dismounting large-sized nuts and bolts which are employed in high-powered rolling mills, various types of power-operated wrenches have been developed and employed, conventionally e.g. a mechanical wrench which includes planetary gears for exerting multiplied force or a hydraulic-operated wrench which rotates the bolts intermittently.
However, such wrenches require the wrench body to be equipped with a different type of bolt-driving element between the fastening and dismounting operation. Namely, such a wrench necessitates the frequent replacement of the bolt-driving elements so that the fastening or dismounting operation has been cumbersome and time-consuming.
It is an object of the present invention to provide a wrench which can resolve the above disadvantages such that it can efficiently conduct the fastening and dismounting operation substantially without incurring the replacement of the bolt-driving element.
It is another object of the present invention to provide a wrench which has a simple and rigid construction consisting of a hydraulic actuator, a drive lever and a reaction force lever and therefore can be manufactured at low cost.
It is still another object of the present invention to provide a wrench which can exert the optimal fastening or dismounting force onto bolts such that the force exerted by a hydraulic actuator, which imparts a torque to the bolts, is always held in a direction perpendicular to the longitudinal axis of the drive lever.
It is a further object of the present invention to provide a wrench which can automatically conduct the fastening or dismounting of bolts without employing any electric or electronic means such as solenoid valves or relays.
Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings.